lucyb lucyb - 4 months ago 7
HTML Question

How to return values from external javascript function

I have a function in an external java script file and I dont know how to call and return the value that my function returns in text properly. When I click place order, I want the values to be calculated by my function and then the final value to be displayed underneath the place order box. I can get my function to alert if I enter nothing but I can't get it to return my final value- what am I doing wrong?



function sum2()
{
var one = document.getElementById("book_1").value;
var two = document.getElementById("book_2").value;
var three = document.getElementById("book_3").value;

if ((one == "")||(two == "")||(three == ""))
{
alert ('Error', 'values missing');
}
else
{
var sum1 = one * 19.99;
var sum2 = two * 86.00;
var sum3 = three * 55.00;
var sum = sum1 + sum2 + sum3;

document.getElementById('output').value = sum;
document.write(sum);
}

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Work</title>
<script type="text/javascript" src="ex4.js"></script>
</head>
<body>
<div id="container">
<h2>Order Books Online</h2>
<form action="" method="post" id=”frm”>
<fieldset>
<table border="0">
<tr>
<th>Book</th>
<th>Quantity</th>
<th>Price</th>
</tr>
<tr>
<td>Basics of C++</td>
<td><input type="text" size="3" id="book_1" /></td>
<td>$19.99</td>
</tr>
<tr>
<td>Program Development in Perl</td>
<td><input type="text" size="3" id="book_2" /></td>
<td>$86.00</td>
</tr>
<tr>
<td>Advanced JavaScript</td>
<td><input type="text" size="3" id="book_3" /></td>
<td>$55.00</td>
</tr>
</table>
<br /><br />
<input type="submit" onclick="sum2(); return false;" value="Place Order" id="sub" />
</fieldset>
</form>
</div>
</body>
</html>




Answer

Try this, its working, output is displaying on last.

function sum2()
{
      var one = document.getElementById("book_1").value;
      var two = document.getElementById("book_2").value;
      var three = document.getElementById("book_3").value;

      if ((one == "")||(two == "")||(three == ""))
      {
        alert ('Error', 'values missing');
      }
      else
      {
         var sum1 = one * 19.99;
         var sum2 = two * 86.00;
         var sum3 = three * 55.00;
         var sum = sum1 + sum2 + sum3;

         document.getElementById('output').innerHTML = sum;
        // document.write(sum);
        }
}
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <title>Work</title>
    <script type="text/javascript" src="ex4.js"></script>
  </head>
  <body>
     <div id="container">
     <h2>Order Books Online</h2>
     <form action="" method="post" id=”frm”>
       <fieldset>
       <table border="0">
         <tr>
           <th>Book</th>
           <th>Quantity</th>
           <th>Price</th>
         </tr>
         <tr>
           <td>Basics of C++</td>
           <td><input type="text" size="3" id="book_1" /></td>
           <td>$19.99</td>
         </tr>
         <tr>
           <td>Program Development in Perl</td>
           <td><input type="text" size="3" id="book_2" /></td>
           <td>$86.00</td>
         </tr>
         <tr>
           <td>Advanced JavaScript</td>
           <td><input type="text" size="3" id="book_3" /></td>
           <td>$55.00</td>
         </tr>
       </table>
       <br /><br />
       <input type="submit" onclick="sum2(); return false;" value="Place Order" id="sub" />
       </fieldset>
      </form>
     </div>
    <div id="output"></div>
  </body>
</html>

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